#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
int main()
{
	int i,sum = 0;
	int arr[10] = {0};
	//scanf("%d", &arr[10]);
	for (int i = 0; i < 10; i++)
	{
		scanf("%d", &arr[i]);
		sum += arr[i];
	}
	float sz =(float) sizeof(arr) / sizeof(arr[0]);
	printf("%f", sum/sz);
	return 0;
}